Note 5 - Fair Value of Financial Instruments - Fair Value of Available-for-sale Securities (Details) - USD ($)
Jun. 30, 2021
Mar. 31, 2021
Total $ 62,756,448 $ 64,860,822
Less than 1 year 25,293,411  
1-3 years 27,108,299  
3-5 years $ 10,354,738